The advantages of injecting water vapor into fossil fuel burners is known. A number of devices are now on the market for this purpose, some operating on a suction principle, while others operate on pressure. The present invention relates to the former type, and devices of this type are expensive and cumbersome to maintain and regulate. To my knowledge, prior devices have had an additional handicap if more than one burner is to be serviced. One device per burner is required.